1. Field of the Invention
The present invention relates to a composition, a process for producing a sheet, a sheet, a laminate, and a laminate with a device wafer. More specifically, the present invention relates to a composition, a process for producing a sheet, a sheet, a laminate, and a laminate with a device wafer, each of which can be preferably used in the production of a semiconductor device or the like.
2. Description of the Related Art
In the production process of a semiconductor device such as an integrated circuit (IC) or a large-scale integrated circuit (LSI), a large number of IC chips are formed on a device wafer and individualized by dicing.
With the needs for further miniaturization and higher performance of electronic devices, there is a demand for further miniaturization and higher integration of IC chips mounted on electronic devices, but the high integration of an integrated circuit in the plane direction of a device wafer is close to the limit.
As a method for an electrical connection of an integrated circuit in an IC chip to an external terminal of the IC chip, a wire bonding method has been heretofore widely known. In order to miniaturize the IC chip, in recent years, a method in which a through hole is provided in a device wafer and a metal plug as the external terminal is connected to the integrated circuit so as to pass through the through hole (a method for forming a so-called through-silicon via (TSV)) has become known. However, with the method for forming a through-silicon via alone, the needs of higher integration for the IC chip in recent years as described above have not been sufficiently fulfilled.
In consideration of these things, there is known a technique of improving the integration density per unit area of the device wafer by making the integrated circuit in an IC chip multi-layered. However, since a multi-layered integrated circuit increases the thickness of the IC chip, reduction in the thickness of members constituting the IC chip is required. As to the reduction in the thickness of the members, for example, reduction in the thickness of the device wafer has been studied and is promising not only to lead to the miniaturization of an IC chip but also to save labor in a through-hole producing step of the device wafer in the production of the through-silicon via. Further, a thickness reduction has also been attempted in semiconductor devices such as a power device and an image sensor, from the viewpoint of improving the integration density and improving the flexibility of device structures.
A wafer having a thickness of approximately 700 to 900 μm is widely known as the device wafer. In recent years, for the purpose of miniaturization of an IC chip, it has been attempted to reduce the thickness of a device wafer to 200 μm or less.
However, a device wafer having a thickness of 200 μm or less is very thin and thus, a member for producing a semiconductor device using such a device wafer as a base material is also very thin, and therefore, in a case, for example, where the member is subjected to an additional treatment or where the member is simply moved, it is difficult to support the member stably while not damaging the member.
In order to solve the problems as described above, there is known a technique in which a device wafer before reducing the thickness thereof is temporarily fixed (temporarily bonded) to a support substrate with a temporary bonding material, a rear surface of the device wafer is ground to make it thin, and then the support substrate is dissociated from the device wafer.
JP2014-37458A discloses the attachment of a wafer to a support substrate of the wafer using an adhesive film which has an adhesive layer formed using an adhesive composition containing a styrene-based elastomer, ethyl acetate, and decahydronaphthalene.
On the other hand, JP 1999-117180A (JP-H11-117180A) discloses the production of a sheet-like material in which a fibrous base material is impregnated with a styrene-based elastomer dispersion solution containing 150 to 2,400 parts by weight of an organic solvent, 100 to 1,500 parts by weight of water and 1 to 20 parts by weight of a nonionic surfactant having a Hydrophile-Lipophile Balance (HLB) value of 6 to 17 with respect to 100 parts by weight of the styrene-based elastomer, and then dried.